Saturday, April 01, 2006

Knowing Sentences

J.L. Dowell, in her Meaning, Reason, and Modality, raises an objection to Chalmers' 2-D semantics. Chalmers defines the apriority (hence 1-necessity) of a sentence-token in terms of the apriority of the thought it expresses. But Dowell points out that we cannot know a priori what the associated thought of a given sentence is. So 1-necessary sentences won't themselves be a priori knowable, thus (allegedly) breaking the link between meaning and reason which Chalmers wants for his "golden triangle".Dowell writes:

To help focus the issue, consider first a clear case of a sentence-token’s being a priori, but not a priori knowable in the above senses. Suppose that Leverrier writes in his diary

(N) “Neptune is the planet, if any, that perturbs the orbit of Uranus”.

Let us suppose further that Leverrier has introduced “Neptune” into his idiolect as a name for whichever planet, if any, perturbs the orbit of Uranus. Given this, the thought expressed by N is both a priori and has a necessary epistemic intension (since it expresses the thought that the planet, if any, that perturbs the orbit of Uranus is the planet, if any, that perturbs the orbit from Uranus).

However, Dowell continues, anyone reading the diary has no way to know a priori, i.e. without experiential justification, what thought (N) expresses. (Indeed, she doesn't say it, but presumably we cannot even know what language it's written in. For all anyone knows a priori, the squiggles might have landed on the page through a massive coincidence of spilt ink, and so not mean anything at all.) So although (N) is a priori in Chalmers' thought-derived sense, the sentence itself is not a priori knowable. Someone presented with the sentence could not determine a priori whether it was true; first they would need to know what it means.

Dowell then argues:

[I]t is unclear how the a priority of sentence-tokens in Chalmers’ sense is a rational notion at all, given that it is divorced from what is a priori knowable and not characterized in terms of rational accessibility to agents, even idealized ones.

But this is silly -- Dowell is asking the impossible. On (my understanding of) her characterization of what it would take to know a sentence a priori, there are no a priori knowable sentences. So Chalmers' conception of sentence apriority is divorced from ["what is a priori knowable", namely:] nothing at all!

The core issue here concerns what sort of link we could hope to establish between reason and meaning. Dowell begins with the question of whether the 2-D framework can "ground an a priori-accessible, extension-fixing component of content for very many of our terms and sentences." But to ask that reason alone tell us the meaning of squiggles is certainly too demanding. It would be ludicrous to hold that sentence apriority is a matter of being able, when presented with some squiggles, to determine by reason alone whether the claim made by the squiggles is true.

No, we should be satisfied to make more modest demands on reason. A more reasonable challenge is to ask whether there is a component of content that is constitutively tied to apriority in the sense that Chalmers describes. Dowell complains that "this interpretation presupposes rather than grounds an a priori available component of content." But that only seems an objection if we misunderstand the aim of the framework. If what it takes for a component of content to be "a priori available" is for an agent to be able to determine the content of squiggles by reason alone, then (obviously!) no-one can provide such a thing, and nobody is trying to.

It might help here to invoke the distinction between semantics and meta-semantics. Whereas first-order semantics concerns the meaning of expressions, meta-semantics asks about how words get assigned their meanings to begin with (cf. the problem of intentionality). Now, Dowell is effectively demanding an a priori method for answering metasemantic questions (e.g. does some token of 'tiger' mean to talk about big cats or sofas?). But that's a ridiculous demand. We can all agree that such meta-semantic determination is an empirical matter. (Dowell calls this "the incontrovertible point".)

No, the only reasonable question to ask here is the first-order semantical one. Given that the words 'tiger' and 'sofa' actually have such-and-such semantic content (in particular, their respective primary intensions), can we determine whether "tigers are sofas" is a priori false, just in virtue of the meaning of the terms? Plausibly, we can. Perhaps a tiger carcass could be used in sofa manufacture, but I can't imagine any scenario in which it would turn out that tigers just are sofas. (Again, don't confuse this with the meta-semantic issue of whether we can imagine scenarios where the word 'tiger' would turn out to mean something completely different.)

Another way to put the point is to insist that our idealized agent be granted full command of the language in question. Perhaps Dowell intended to allow agents a coarse-grained version of the language, such as that which is shared by all competent English speakers. That would suffice to allow us to identify sentences like "Hesperus is Hesperus" as a priori, but not speaker-relative apriorities such as that expressed by (N). The problem with this is that it excludes a key component of meaning (according to the 2-D framework), namely, the 1-intension. Chalmers is explicit that 1-intensions are speaker-relative (hence the need to speak of sentence tokens rather than types), so the appropriate "language" will need to be fine-grained enough to accommodate this. In other words, the agent needs to be given the idiolect of the speaker.

Then the relevant question becomes whether an idealized agent who reads (N) in Leverrier's idiolect could, through a priori reasoning alone, come to know that (N) is true. And the answer is surely 'yes'. A perfectly competent speaker of Leverrier's idiolect will grasp the primary intension of 'Neptune' so used, and thus recognize the thought expressed by (N) as being 1-necessary and hence knowable a priori. This seems to be "an interpretation that genuinely links reason [and] meaning... in a substantive way." Of course if we strip a sentence of its meaning, then our rational notions can get no grip on it. But that does nothing to cast doubt on Chalmers' links between meaning, reason, and modality. The claim isn't that reason can magically discern the meaning of squiggles. Rather, it is that reason can determine whether, given the meaning of a sentence, it must be true. This establishes substantive connections between the semantic notion of a primary intension, the rational notion of apriority, and the modal notion of 1-necessity.

Related Posts by Categories

4 comments:

Hi, Richard. Thanks for your interesting comments. It looks to me like you've run together aspects of distinct arguments with distinct targets in my paper. (So you're readers can decide what they think about these issues for themselves, here's a link to my paper: www.bgsu.edu/departments/phil/faculty/dowell/MRM.htm.)

Your remarks pick up too many distinct threads in my paper for me to address them all. So let me focus on the issue that arises in the discussion of the Leverrier example that you cite. There I am distinguishing between a sentence-token's being a priori, in Dave's sense, and its being a priori knowable in the sense of being capable of being conclusively non-experientially justified on ideal rational refection. This account of a priori knowability just picks up on what it is for a thought to be a priori, according to Dave. On p.98 of 12/24/05 version of 'The Foundations of Two-Dimensional Semantics' available on Dave's webpage, he says "A sentence-token is a priori when it expresses an a priori thought. A thought is a priori when it can be conclusively non-experientially justified on ideal rational reflection".

So, for Dave, what it is for a sentence to be a priori is not the same as what it is for a thought to be a priori. Moreover, sentences are not a priori, according to Dave, in the sense in which thoughts are, that is, they are not what I am calling 'a priori knowable'.

The question is: Is a sentence's being a priori, but not a priori knowable enough to forge a connection between reason and a sentence's meaning in any interesting sense? What we need is some account of what it is to have forged such a link that does not presuppose that there is one. To say, as Richard does, that "a perfectly competent speaker of Leverrier's idiolect will grasp the primary intension of 'Neptune' so used, and thus recognize the thought expressed by (N) as being 1-necessary and hence knowable a priori" is to presuppose that there is such a thing as a component of the content of Leverrier's token of "Neptune" that is constitutively linked to reason.

As an fyi to your readers, I of course never say that Dave's claim is that 'reason can magically discern the meaning of squiggles'. The problem for the person reading Leverrier's diary is that they can perfectly well understand Leverrier's token of 'Neptune is the planet, if any, that perturbs the orbit of Uranus' and to fail to know sentence-token's truth a priori, even in the very generous sense of 'a priori knowable' given above.

I don't think Dave disagrees with any of this. Where I think he disagrees is in thinking that it is enough to forge a link between meaning and reason to have shown that a sentence-token's being a priori in his sense is linked to the a priori knowability of the thought it expresses. That's what I'm casting doubt on in the relevant portion of my paper.

Hi Janice, thanks for the clarifications, and my apologies for any misinterpretations on my part. I'm still a little unclear on what it would take for a sentence to be "a priori knowable" in your sense. It seems to me that whether or not an a priori sentence is so knowable will depend on how much of its meaning we allow the reader to grasp. You agree that it would be absurd to ask them to discern its truth solely from the physical ink-patterns. So we must be giving them some content.

It sounds like you want to go with with the "course-grained" common language option, discussed in my post. But as I object there, this seems to pre-emptively exclude the sorts of speaker-relative primary intensions that are crucial (according to the 2-D framework) for cases like (N).

So it seems question-begging whatever answer we give. You worry that my response "presupposes" that there are such components of content, and I worry that your argument presupposes that there aren't. Where's the neutral ground from which one could try to "forge" the required connection in a non-question-begging way? I'm just not clear on how your challenge is a reasonable ask.

Hi, again. "A priori knowable" is just another name for Dave's notion of a priori as it applies to thoughts. My idea is that we can take Dave's notion and detach it from its target and see whether it applies to anything besides thoughts. I don't think I'm disagreeing with Dave in thinking that sentence-tokens aren't a priori knowable in this sense, that is, that they aren't a priori in the same sense that thoughts are a priori. That's just what I read him as saying in the passage I quoted in my earlier post. (fyi, if anyone is interested in knowing more about what Dave's notion comes to, he's got a helpful discussion following that quoted passage.)

So I don't think whether sentence-tokens are a priori knowable in the reserved sense is a source of disagreement between Dave and myself--we both think they aren't. The source of disagreement is over whether, given that Dave's Core Thesis is stated for sentences, not thoughts (it says that for any sentence S, S is a priori iff S has a necessary 1-intension)and given what it is for a sentence-token to be a priori in Dave's sense (i.e. NOT a priori knowable) we should think that the truth of that thesis links meaning and reason in any substantive way. I'm not claiming I've got a knock-down proof that it doesn't. What I do think, though, is that we need some further reason to think that it does. (fyi to others: I canvass a couple of things one might have in mind as forging such a connection in my paper, but don't see how they could be what Dave has in mind.)

A final fyi: I'll be giving a shortened version of this paper at the upcoming American Philosophical Association's Central Division meeting in Chicago. So if anyone who will be attending has further thoughts about these issues, I'd love to hear them. There will also be what should be an interesting discussion of Soames's anti-2-D book featuring Dave, Bob Stalnaker, and Soames later the same day.

That doesn't really address my concerns. It all seems to come down to what one thinks is required for a "substantive connection" between meaning and reason. One proposal (yours?) is to demand that 1-necessary sentences be knowable a priori, i.e. the sentence token "can be conclusively non-experientially justified on ideal rational reflection".

But you've never explained what sort of a priori grasp of the sentence we are giving the agent here. (Sorry to sound like a broken record, but it's an important point, and I'd be interested to hear your response to it.) The most basic interpretation would be to demand that an agent discern the sentence's truth value a priori, given the physical token (ink on a page). But that would require magical a priori squiggle-reading skills, which you agree is absurd. So you mustn't mean to demand that. You are committed to building more in to the sentence token, making its meaning "transparent" somehow, perhaps by allowing the agent to have a full grasp of the language it was written it.

But we have a dilemma. Either you include the primary intension in what's given, or you don't. If you do, then (N) is a priori knowable. And if you don't, then you're just begging the question against such semantic values, and it isn't clear why we should care that the sentence isn't "a priori knowable" in that sense. As with the squiggle case, it's just an unreasonable ask, and we shouldn't think that a "substantive connection between meaning and reason" should depend on that.

So how's this alternative proposal: a substantive connection here would be satisfied if we meet the criterion that "reason can determine whether, given the meaning of a sentence, it must be true." Why prefer your proposal to this one, especially if no-one would ever dream that yours could be satisfied in any case? Perhaps I'm missing something, but I just don't see the force of your argument.

Visitors: check my comments policy first.Non-Blogger users: If the comment form isn't working for you, email me your comment and I can post it on your behalf. (If your comment is too long, first try breaking it into two parts.)